KOPPRIO German Adolfo
congresos y reuniones científicas
Uncertain future of fish populations in Argentinean coastal lakes: The impact of severe droughts and floods
LARA, R. J.; KOPPRIO, G.; STRUSSMANN, C. A.; FREIJE, R. H.
Simposio; Climate change effects on fishes and fisheries: Forecasting impacts, assessing ecosystem response and evaluating management strategies; 2010
PICES, ICES, FAO, FRA, HUGCOE
Climate change impacts fish dynamics and represents a challenge of faster thermal adaptation for South American fish. The Argentinean pampas had registered increasing rainfall and severe floods during the last 3 decades. However, since 2007 a rigorous drought affects the region. Chasicó Lake belongs to an endorreic basin particularly sensitive to hydrologic alterations, responding with dramatic changes in extension and salinity. In 1963, Chasicó was a hypersaline water body of ~3000 ha, devoid of fish due to salinities of ~100 g L-1. After the floods, it expanded to ~12,000 ha and salinity decreased to ~20 g L-1. Odontesthes bonariensis entered the lake through Chasicó River after the inundations and found the moderate salinities that favor its growth at early development stages. This resulted in few years in a drastic increase of fish size and stock and shifts in stakeholder structure. During the current dry phase, 2009 underwent the worst drought of the last 7 decades. This worsened the natural eutrophic state of pampean water bodies and increased their salinity. Particularly in the shallower lakes, severe fish mortalities occurred, likely due to high temperature, anoxia and/or toxic cyanobacteria blooms. During 2007 and 2008 the water level in Chasicó decreased about 1 meter and salinity increased to 23 g L-1. The sensitive response of this ecosystem to the increment of droughts and inundations predicted for the late 20th century illustrates its potential as indicator of future coastal changes that could generate new risks or opportunities for fish populations and man.